Application and numerical method of chemical non-equilib rium flow for Teflon ablative flow fields in near-space flying condition

Abstract

A numerical method has been established and applied to compute the chemical non-equilibrium flow involving Teflon ablative effect, where the chemical non-equilibrium Navier-Stokes equation is solved by taking account of 23 species including the ablative products. The computational results of electron number density in the plasma sheath for the sphere-cone RAMC-II are well compared with those of flight experiments. The reliability of the present method has been validated in near-space flying condition, and the varying feature of the electron number density with flight altitude has been revealed. The present numerical method is applied to compute the Teflon ablative flow field past sphere-cone body with different altitudes of 25–70 km. It is indicated that the effect of ablative products on electron number density is mainly limited in the region of boundary layer while the phenomena of Teflon ablation are obvious at moderate and low altitudes. The decrease of temperature in the boundary layer is caused by the Teflon ablation which results in the increase of the number of negative air ions. On the other hand, the number of F? from electrophilic species of Teflon-air reactive mixtures increases continuously with the decrease of flying altitude. These factors cause the reduction of electron number density in the boundary layer.